The present invention relates to a system operable with air-conditioning and refrigeration equipment. More specifically, the system provides a method and apparatus for coupling a thermal storage system, such as an ice-storage apparatus or other low-temperature reservoir, to existing cooling refrigeration devices to enhance their performance and efficiency; reduce input energy at the same operating capacity or expand the operating cooling capacity at the same energy input; and, to particularly reduce power demand at "peak operating or usage periods" noted by power generating operators. The system is also adaptable to new installations for realization of similar benefits for the "design" capacity of such new installations.
An illustration and explanation of the need for expansion of the range of existing cooling devices is provided in a brochure from the Electric Power Research Institute, "Supermarket Air Conditioning and Dehumidification". The modern convenience of the grocery store or supermarket with its air-conditioned aisles, glassed or open-front freezers and display cases, and its cold-storage lockers is accepted and expected by consumers. However, the costs to install, operate and maintain these several, usually large, cooling and refrigeration apparatus are significant. Several alternative systems for supermarket cooling requirements are illustrated and discussed in the above-noted brochure, which suggestions include notations on capital and operating costs, as well as a discussion of the relative advantages and disadvantages of the several systems. In this brochure, the utilization of an ice-storage or cool storage system is briefly discussed, however, there is no illustration or description of an operable system, only a recognition of the potential benefits from such a system.
Conventional cooling apparatus generally consists of stand alone devices, such as air-conditioners, and individual assemblies, each having its own cooling circuit, power connections and ductwork for air transfer. The coupling of an ice-storage apparatus, or other low-temperature reservoir as compared to the ambient environment temperature reservoir, to an existing cooling unit can reduce its period of operation to attain the same cooling capacity, thus reducing its energy consumption during a peak electrical cost period, for example; or alternatively, it can be viewed that the operating range of the unit is expanded, which results in a "larger cooling capacity" unit without replacement of existing equipment. In addition, utilization of the ice-storage apparatus can reduce input energy at the same or increased output cooling capacity. Further, multiple cooling devices can be connected to this noted thermal storage system or low-temperature reservoir for simultaneous operation therewith. Illustrative of a familiar facility with multiple cooling or refrigerant utilizing devices is the above-noted supermarket or grocery store, which commercial facilities frequently have air-conditioning apparatus, freezers or coolers with a door for goods, such as ice-cream, open coolers for dairy products and frozen juices, and sub-zero coolers for storage of other foodstuffs. In a new installation, the size and configuration of some or all of the ancillary cooling-type devices coupled to an ice-storage system, low-temperature reservoir or other thermal storage arrangement can be reduced in size or rated capacity to deliver the required cooling capacity associated with cooling/refrigeration systems, which may generally include or incorporate compressors, condensers, cooling towers and other apparatus without a thermal storage system. However, the "rated capacity" of a standard cooling/refrigeration system required to achieve the same cooling capacity of a system coupled to a thermal storage system will be greater, and, as a consequence, the requisite capital expenditure for such a cooling system would be expected to be greater. Arguably the capital cost of the thermal storage system would offset any capital savings associated with the smaller heat exchange system, however, the operating cost is demonstrably lower for the thermal storage/heat exchange system. Alternatively, a smaller input energy could be utilized to obtain the same or greater "rated or design" capacity.
This above-noted reduced operating cost is reflective of lower input energy requirements for the cooling/refrigeration system to operate at a prerequisite cooling capacity. The necessity for such lower operating conditions and costs is an ever-increasing consideration for any power-using operation, as the consumable parameter, usually electrical energy, has continually increased in cost, while its relative availability is diminishing. As an example, the increasing frequency of "brown-outs" in certain sections of the United States illustrates the lack of available power to keep up with the increased consumer demand especially during the midafternoon period of warm summer months. In addition, the ability to expand or couple the usage of an ice-storage system to several parasitic apparatus; the ability for thermal storage potential during off-peak-usage periods of electrical power usage would result in reduced power costs to provide cooling capacity at the same cooling demand level; and, the relatively nominal capital cost of thermal storage equipment in comparison to other cooling equipment are all factors weighing in favor of the consideration of coupling thermal storage equipment with extant cooling systems.